Measuring device



C. T. ALLCUTT MEASURING DEVICE Feb. 2 1926.

Filed March 31. 1920 F/QZ INVENTOR Chester TIN/c077? ATTORNEY PatentedFeb. 2, ii26.

UNITEQ earner FFlQEQ CHESTER '1. ALLGUTT, F EPITT3BURGH, PENNSYLVANIA,ASSIG'NOR TO lNESTKNG- HOUSE ELECTRIC & MANUFACTURING GQMPANY, &COBPGRATION 81F PENNSYL- VANIA.

HEASUZ'RING DEVICE.

To all whom it may concern:

Be it known that I, Crrns'rnn T. Annoo'rr a citizen of the UnitedStates, and a resident of Pittsburgh, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inMeasuring Devices of which the following is a specification.

My invention relates to measuring systerns and particularly to means formeasuring the symmetrical components of unbalanced polyphase-quantities.

()ne ob ect of my invention is to provide means whereby standardinstruments and transformers may he used for measuring the symmetricalcomponents of an unbalanced polyphase system Another object of myinvention is to pro" vide a system, of the above indicated character,that shall be simple and inexpensive to construct and effective in itsoperation Letters Patent- No. 1,535,593 issued April 28th, 1925, uponthe copending application of G L. Fortescne, L. W. Cinho and Slepian,discloses and claims broadly means for determining the symmetricalcomponents of an unbalanced polyphase quantity.

In my present invention, 1 utilize broad principles set forth in theahovmentioned application, but obviate the necessity for the use ofrotating apparatus es disclosed, in the aloov anentioned application an,lso reduce the apparatus necessary to 0.1 the desired result to aminimum special devices.

in practicing my invention, It sten(innit measuring instrument eqnalimpedance devices differ i by an. that depends upon of: phases in thecircuit, vvl'iic nected to the cirthe mete is actuate syrmnetricalcomponent trical quantity imp changing the coin to the circuit, theanstrnrneni ed to inclica either the pr-ota o alcomp n haianced oncomponent the current a nnhalence of the circuit, the negativerotational current Serial Ito. 370,229.

tive rotational current is the unbalance factor of the circuit and maybe used to com puts the charge to he made a customer for energyconsumed. Figure 1 of the accompanyin; drawings is a diagrammatic viewof an electric circuit embodying my invention; Fig. 2 is a diagrammaticview of an electric circuit; embodying an improved form of my inventionfor indicating current values, and Fig 3 is a diagrammatic view of anelectric circuit showing an improved form of device for in dicatingvoltage values A three-phase circuit 1 comprises conductors 2, 3 and 41:across which an unbalanced voltage is impressed or which is so unequallyloaded that the voltage thereacross is unhal is connected between "to snced. A voltmeter o the conductor 2 and a point 6 in a circuit ernetwork 7. The circuit 7 is connected between the conductors 3 and *3:and comprises a resistor 8, a reactor 9, a resistor i and a condenser11. resistor 8 and the reactor Y comprise an impedance device 12 thecurrent traversing which is 120 out of n? ass With respect to thecurrent traversing the impedance devicelfi comprising the resistor P3and the condenser 11 The impedance devices 12 end are of equal ii:pedance. ln other words, the network or circiiit '1? has point t;therein which t net as the concuotor 01 t to which net the a balancedpoiyphase voltage or "'1 ion of cnase rotati n is applied t Nocurrentwill traverse the ii l balanced conditions but inclice te when the circehas been observed ill equal voltages that are 60 out of phase. Since theimpedances 12 and 13 have equal absolute values and differ in phase in120, they are traversed by equal currents t at are exactly in phase or180 out of phase, depending upon the phase rotation of the circuit 1 andthe connection of the impedances thereto. If the impedances 12 and 13are so connectedthat the currents traversing them cancel under balancedconditions, no current will traverse the instrument 5 under suchconditions, and under unbalanced conditions, a. current that isproportional to the negative rotational component Will traverse theinstrument. in systems having a difierent number of phases, theimpedances 12 and 13 should differ in phase by the angle neces sary tobring the currents traversing the same exactly in phase or 180 out ofphase under balanced conditions. In other Words, the iinpedances 12 and13 difi'er in phase to degree that is correlated to the number of phasesof the circuit.

In Fig. 3 of the drawings, two potential transformers 14 and 15 have theprimary windings 16 and 1'2 thereof connected in open delta to thecircuit 1. The secondary windings 18 and 19 are connected to a networkor circuit 20 comprising impedances 21 and 22 of equal absolute values,the phase angles of the currents traversing which differ by 60. Whilethe impedance device 22 is shown as non-inductive and the device 21 asinductive, such is not necessary as any impedance devices may beemployed having such characteristics that the currents traversing thedevices or the voltages thereacross shall be angularly displaced by 60.The voltmeter 5 is connected from a point 23 intermediate the impedancedevices 21 and 22 to a point 24 intermediate the windings 18 and 19 ofthe transformers. The transformer winding 18 is reversed in itsconnection in order to so shift the phase-angular relation of thevoltage applied to the inpedancc and the impedance 22 that the same rnavbe 80 out of phase with each.

other instead of 12 out of phase. This eliminates the necessity ct usinga condensive reactant-e. In other Words, the impedances 21 and 22 may berelatively small. in size ch would not be the case if a condenseri'mLU-fi used. This is, oil course, obtained by the use of the standardinstrument transformers and 15. The points 23 and of seine potentialwhen a balanced voltage one direction huse rates. :1. is ap lied to thecircuit, they of nt potential when an unbalanced voltto the circuit 1and, conse L deter trav by current vonags. simplest r" the unbalancedpolyphase quantities with the use of standard meters and transformersand with the use of relatively small impedance devices.

In Fig. 2 of the drawings, the secondary windings 25 and 28 of seriestransrormers 27 and 28 that are associated with the conductors 3 and 4of the circuit 1 are connected to a current-measuring instrument 29. Twoequal impedance devices 30 and 31 of desired characteristics areconnected in series across the instrument 2%, and the point 32therebetween is connected, through a conductor to a point 34: betweenthe windings 25 and 26.

The characteristics of the impedances 30 and 31 are such that when abalanced current traverses the circuit 1, no current traverses theinstrument 29 but, when an unbalanced load is impressed on the circuit1, current traverses the instrument 29 and is a measure of the unbalanceof the circuit 1. In other WOI'ClS, the instrument .29 may indicate thepositive or negative rotational component of the unbalanced currenttraversing the circuit 1, depending upon the connection of thetransformers 27 and 28. The negative rotational component of the currentis a measure of the unbalance of the circuit, and the ratio of thenegative rotational current component to the positive rotational currentcomponent is the unbalance factor and may be used as a measure forpenalizing a customer for taking his load on a single phase basis ratherthan on a balanced polyphase basis. F or a difierent number 01 phases,the characteristics of the iinpedances 30 and 31 are so chosen that,when connected to measure the negative rotational com-- ponent, nocurrent traverses the instrument 29 under balanced conditions.

My invention is not limited to the specific structures illustrated as itmay be variously modified Without departingtrom the spirit and scope ofthe same, as setforth in the appended claims.

I laim as my invention:

1. in a three-phase circuit, the combination. with measuring instrument,of a network connected across two conductors of the circuit of suchcharacter that one point of the network is of the same potential as theother conductor of the circuit when a balanced th 'ee-pliase voltage isapplied to the circuit, and means for connecting the messinstruinentacross the points of canal potential. m

2. In a thre Jhase electrical circuit, the tion with. electro-responsvedee, oi two secondary tmrslfornier windings :cnnectcn that the'currentsand means for or -Ii q a nerve device from a point hetWeel-L impedancemeans and a point between the windings.

3. A measuring network for an unbalanced three-phase circuit comprisingtwo transformers the primary windings'of which are connected inopen-delta to the circuit, two impedance devices of different phasecharacteristics connected in series with the secondary windings of thetransformers, and a voltmeter connected from a point between theimpedances to a point between the secondary windings one of which isreversed to obtain a phase difierence therebetween of sixty degrees.

4. The combination with a polyphase circuit, of means including a staticnetwork comprising a plurality of impedance devices, said means beingconnected to less than all of the circuit conductors, and the devicesbeing so connected to the network and having such characteristics that,under balanced conditions in the circuit, predetermined points of thenetwork will have the same relative potentials as a predeterminedconductor of the circuit to which conductor the network is notconnected, and electro-responsive means connected between said points ofthe network to be subjected to the potential difference between saidpoints of the network when the circuit conditions are unbalanced, saidpotential ditl'erence being a measure of the unbalance of the circuit.

5. The combination with an N-phase circuit, of a static networkconnected thereto comprising a lurality of impedances differing in phase0 aracteristics by an angle that is correlated to the number of phasesin the circuit, and a device so connected to the network as to beinfluenced by a force that is proportional to one s mmetrical componentof an electrical quantity of the circuit.

6. The combination with a polyphase circuit and an electro-responsivedevice, of means for energizing said device in accordance with asymmetrical component of the voltage of the circuit comprising two equalimpedances of different phase characteristics connected together andsubjected to the voltages of two separate phases of the circuit, thecommon point of said impedances being connected to said device.

7. The combination with a three-phase circuit and an electro-responsivedevice, of'two potential transformers connected across two phases ofsaid circuit, two equal impedances differing in phase by 60 connectedtogether and to said transformers, and connections between 'said deviceand the common point of said impedances.

8. The combination with a polyphase circuit and an electro-responsivedevice, of two potential transformers connected across two phases ofsaid circuit, two equal impedances difierin in phase by an angle equalto the phase isplacement of the voltages of'said two phases underbalanced conditions when one of said voltages is reversed in sign, saidimpedances being connected together and to said transformers, andconnections between said device and the common point of said impedancesto energize said device in accordance with one phase-sequence componentof the voltage of said circuit.

In testimony whereof, I have hereunto subscribed my name this 13th dayof March 1920.

CHESTER T. ALLCUTT.

